i currently have two jl 10s in a sealed box and i went on jl's website but i dont really understand how the isobarik set up works. the pic they have looks like the sub surrounds are touching and i dont see how they can work like that and if i did set it up that way would it sound any better/louder/clearer.

Well basically Isobarik speaker loading is when you have 2 speakers with their cones facing eachother, and the subs are right on top of one another. The most benificial purpose of this setup is to cut down on box size. With a isobarik setup, you can use 2 subs in a box, and have HALF of the reqired airspace for that of ONE sub. So lets say your one sub needs 1 cuft of airspace. So you have 2 subs, which means for a normal box you would need 2 cuft. Isobarik load them and you can use 1/2 cuft of airspace for both subs in a common eclosure. I have read that this setup can lessen some distortion, and some slight gain in SPL, but i never cared for this type of setup really. It is a really good space saver though. And as for wiring the subs, you just wire one sub out of phase with the other, meaning one sub you will connect the positive speaker output of the amp to the negative speaker term, and negative to positive. The other sub stays normally hooked up. This way, one subs is pushing outward, and the other sub right across from it is going the same direction.

^^^ yep.

One other note. The reason for an Isobarik box is this :

When a speaker hits, it has to push the air in front of it. The second speaker on top of the first actually pulls the air away from the first, allowing it to hit more freely. Nice design to go with for low air space areas... They hit like crazy. :)

Brian...

but you lose like 6 dB, which is like 4-fold the power, which is also more stress on your alternator.

oh yeah, and you guys forgot to mentiont they look cool :)

>but you lose like 6 dB, which is like 4-fold the power,
>which is also more stress on your alternator.

Explain how this is more stress on your alternator? 4-fold the power?
The wiring is no different then that of any other 2 sub box, with the exception that the exposed sub is wired out of phase which has no effect on the load to the amp.

I think he was implying that because the setup is more inefficient, you would need more power to sustain the same db levels.

I thought 4 "fold" meant the same as 4 "times"...so isobarik would require 4 times the power to get the same db level?....Uhm...not at all :) It will require more, but not 4 times LOL

Quote from MBQuart's website (iain't gonna get into the physics :) ):

"
Compound loading can be applied to any of the enclosure designs described earlier in this section with the benefit of greatly reduced box size. Note that when using these configurations we have to power up two voice coils while the radiating cone area remains the same as a single driver. This results in a 3dB decrease in efficiency as compared to one driver with the same power.
"

-3 dB of using one driver with the same power as you'd be powering the two. But if you invest in two subs then naturally you would use both, so you have another -3 dB (since doubling cone area gives u + 3dB, equivalent to twice the power).

I hope that was clear enough :)

actually, you would (in theory) only loose 3dbs. because each sub is recieving half of the total power, they are only excurting half as much when acting as a single unit, hence the -3dbs.

on that note, it is literally impossible to figure out a db loss or gain based on theory. box size, amt. of power used, interior shape, placment of box within the vehical, etc. all play important roles in the volume level. and to say it will loose 3dbs doesnt apply to the entire spectrum, you could loose 5dbs at 80hz and gain 1 at 40hz, it totally depends on the afformentioned factors.

okay, say you have two subs in a sealed box with 100 W total to both and you're hitting 100 dB (what can i say, you got em at the flea market)

for some reason, you get into your car one day and one is lost/stolen, so you have 1 sub. Luckily you have a jl audio amp that will be able to give that single sub 100W and it will be able to handle it.
Now you have only half the cone area so you're hitting 97 dB

You buy an identical sub the next day and decide to do an isobarik.
If you follow MBQuarts statement (which is proven), you will have
97 dB - 3 dB = 94 dB

if you don't want to take my word for it download a box-building program like winISD.

And yes you're right about the different boxes and frequencies and stuff but thats opensing up a whole other can of worms, we'd have to include that in every conversation, theory works well.

LOL...we are both saying the same thing. i was assuming hes going from a one sub setup to an isobarik one. you are assuming hes going from a 2 sub setup to isobarik. we're both right.;)

ive had winISD for a LOOOOOONG time. excellent tool for box building.

BTW...that pic really kind of scares me.:) i guess if my nip was being bitten i might look the same.